The theoretical formalism of the precession of the polarization vector of spin-\(\tfrac{1}{2}\)  particle in external electric, \(\vec{E}\) , and magnetic, \(\vec{H}\) , fields has been known for a long time [1]}, [2]}, [3]}, [4]}, [5]}, [6]}. In Refs. [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]} this formalism was applied to the case of the bent crystals.
